The developmental interrelationships of putative neurotransmitters, catecholamines, serotonin, acetylcholine GABA and neuromodulator peptides is being elucidated. The metabolism of neurotransmitters will be altered at specific periods of neurochemical and morphological maturation during gestational or neonatal stages by (1) neonatal or intraventricular injections of 6-hydroxydopamine and capsaicin; (2) with the use of neuroleptic drugs that are known to act by blocking dopamine receptors; and (3) placement of discrete lesions in the nuclei of origin of neurons containing dopamine, norepinephrine, serotonin or acetylcholine in 1-3, 10, 21 and 39 day old rats. The hypothesis that the manipulation of biochemical and morphological differentiation during gestational or neonatal stages of growth has long-lasting and/or permanent consequences on normal neurochemistry of brain will be tested.